Can Genetically Modified Mosquitoes Keep Dengue Fever Away From Key West?

Can Genetically Modified Mosquitoes Keep Dengue Fever Away From Key West?

It's a pristine spring morning on the remote tip of Big Pine Key, 30 miles north of Key West. The lone paved road is surrounded by dense brush and wetlands that give way to the Gulf of Mexico. On this particular Tuesday, though, the usually silent landscape is dominated by the pulsing whoosh of a brown and tan helicopter that just touched down. Half a dozen workers in neon safety vests, surgical masks, and sunglasses emerge from the roadside and hustle toward the aircraft. Under the whirling two-blade rotor, they form an assembly line and dump bags of a yellowish substance called larvicide into cone-shaped containers on the sides of the chopper.

This is the modern frontline of the war on mosquitoes — an epic, centuries-long struggle between mankind and nature that has left an indelible mark on the Sunshine State. Minutes after landing, the helicopter is back in the air, buzzing treetops. The pilot banks a tight U-turn, cuts down to an altitude of 60 feet or so, and delivers the payload. As the helicopter bolts out of sight, a barely visible granular trail flutters toward the ground. "Don't look up," says one of the workers on the ground.

The commander in chief of this latest skirmish that's unfolding in the Keys is entomologist (insect expert) Michael Doyle, a slight, mild-mannered Midwesterner with a fastidiously trimmed salt-and-pepper mustache and rimless eyeglasses. Executive director of the Florida Keys Mosquito Control District, Doyle says that about $45,000 will be spent by the end of the day just to counter the onslaught of mosquitoes hatched in the three to four inches of rain that fell over the weekend.

Aedes aegypti is the only species of mosquito in South Florida capable of spreading dengue fever.
Photo courtesy of Oxitec
Aedes aegypti is the only species of mosquito in South Florida capable of spreading dengue fever.
Oxitec's genetically modified mosquito larvae glow fluorescent green and red so researchers can track them.
Photo courtesy of Oxitec
Oxitec's genetically modified mosquito larvae glow fluorescent green and red so researchers can track them.

Back at the agency's headquarters in Marathon, Doyle explains that the larvicide unleashed by the helicopter consists of ground-up corncobs slathered in naturally occurring bacteria that is toxic to mosquito larvae. (It would take a pickup truck-and-a-half of such larvicide to kill a human.) When the pellets land in puddles and nearby water, larvae gobble them up and die before they can morph into the flying, blood-sucking pests we so loathe.

But this method is expensive, labor-intensive, and ineffective against one of the most troublesome mosquito species, Aedes aegypti. Of the 44 species in the Keys, Aedes aegypti is the one that keeps Doyle up at night. It's the stealth bomber of mosquitoes: silent, capable of biting 20 people a day, breeding in the shallow puddles around densely populated residential areas. Most alarming: It's the only species in the region that can spread dengue fever — a nasty and sometimes fatal disease that popped up in the Keys in recent years and could scare away the tourists who drive the local economy.

When Doyle left behind his days at the Centers for Disease Control and Prevention in Colorado, where he studied mosquito saliva, to take charge of the Keys in July 2011, board members who oversee the mosquito program gave him a more than $10 million annual budget, staffers with PhDs, and a fleet that includes four helicopters and two airplanes. They also gave him two orders: Cut the budget while killing more mosquitoes, and ensure that no cases of dengue fever grab headlines like they did in 2009 and 2010.

"The dengue cases were a big deal," Doyle says. "It was the first time [the disease] had been back in more than 60 years. The concern is that the Keys could be a way for dengue to get a new foothold, or a refoothold, in the United States."

Doyle's solution? To move ahead with a controversial experiment that has been in the works since before he arrived: importing and releasing millions of Aedes aegypti mosquitoes that have been genetically modified in the labs of a British biotech firm called Oxitec. These minute marvels of science are tweaked to pass down a gene that causes their progeny to self-destruct soon after hatching. Only males would be released; theoretically, they would breed with normal females and spawn offspring that keel over and die just before adulthood. The dengue-spreading population would collapse generation by generation.

If Doyle's plan goes forward, Key West will be only the fourth site in which these genetically modified insects have been let loose — behind Malaysia, northern Brazil, and the Cayman Islands. But not everyone is eager to tinker with Mother Nature's genetics, perhaps put off by the idea of getting bitten by a mutant mosquito. This is, after all, the Conch Republic — full of sinners, sailors, developers, and assorted rebellious characters who, in 1982, famously declared they were seceding from the United States. Here, the environment teems with beauty and biodiversity, which in turn draw legions of money-spending tourists. Local residents will fight like hell to protect their unique way of life.

Doyle understands the complexity of the situation. "We are in a weird spot, because we want to get rid of dengue and not make headlines...," he says and then adds, laughing, "Then come GM mosquitoes."

As dusk settles over the hordes of sun-soaked tourists lumbering down Key West's boozy Duval Street, an eclectic gaggle of locals, without a formal group name but united in their concern about modified mosquitoes, gathers around a table in a cavernous real estate office. A delectable aroma from a platter of gourmet goodies hangs over the table while ice-cold bottles of Corona are passed around.

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7 comments
Yuwfhan
Yuwfhan

i have not read these articles and i don't claim to know all the facts. You have made the argument that these methods are effective, but are they cheap, pheasible, and most are they safe for other species and the environment. if these mosquitoes are treated with the bacteria is there possibility of this bacteria spreading through a mosquito bite, and if it does will they even have an effect on the bite victims. just wondering

Guest
Guest

There are several cheap, effective and environmentally friendly alternatives to GM mosquitoes. Native plants that repel Aedes aegypti like American Beautyberry can be used as screening to reduce the House Index. A study using repellent plants in Tanzania reduced all mosquitoes found in houses by 50%, the cost was $1.50 per house which includes maintenance and labor costs. This can be used with attractants and lethal ovitraps using used coffee grounds or other cheap environmentally friendly larvicides, as well as fan traps on the lethal ovitraps to not only reduce the larvae survival but also catch the adult females. This push pull method may not only reduce the larvae from surviving, but unlike GM mosquitoes will also target the adult females and reduce the chance of Aedes aegypti entering the home, and at a fraction of the cost.

Other methods include the use of some strains of the fungi Beauveria bassiana and Metarhizium anisopliae which some peer reviewed studies suggest can also reduce the survival of Aedes aegypti offspring, but unlike GM mosquitoes can also cause mortality in the adult females, thus reducing both the population and the chance of being bit.

Yet another example is use of the bacteria Wolbachia, which some peer reviewed studies suggest may reduce the adult Aedes aegypti lifespan by 50% and unlike GM mosquitoes may actually provide resistance against dengue serotype 2 and chikungunya. There are several other alternatives as well.

What Mosquito Control has failed to mention is that releasing millions of GM mosquitoes including thousands of females could potentially increase the risk of transmitting mosquito-borne diseases. Releasing millions of male mosquitoes may also increase the risk of chikungunya which a peer reviewed study suggested can be spread when Aedes aegypti mate. With each male mating as many as 21 times in their lifetime that is a huge risk not worth taking unless the adult female lifespan is significantly reduced or there is resistance against chikungunya, which doesn't appear to be the case for GM mosquitoes. There have been over 100 cases of chikungunya reported in the U.S. between 2006 and 2009 including cases in Florida, so this a very real risk. Florida entomologist Walter J. Tabachnick, estimated that if an outbreak that occurred in Italy had occurred in Key West it would have caused 1,200 cases of chikungunya and 4,000 cases if it occurred during tourist season. The Beauveria bassiana and Metarhizium anisopliae alternatives both reduce the lifespan of the adult female and therefore reduce the chance of chikungunya spreading, they can also be used without releasing more males but instead infecting the already existing males and/or females. The Wolbachia alternative may reduce the lifespan of adult female Aedes aegypti and may even provide resistance against chikungunya, so even if more males were released there would be a significantly reduced risk of spreading chikungunya compared to GM mosquitoes.

There are numerous unknowns such as whether or not the synthetic protein based on sequences from E.coli and the Herpes simplex virus that the GM mosquitoes express could be transmitted to humans during a bite or affect animals ingesting them. As well as a partially independent lab reporting 15% of the GM mosquito offspring surviving in the presence of chicken found in cat food and a member of the mosquito control district admitting that Aedes aegypti have been found breeding in pet dishes, making such an event likely if GM mosquitoes are released. Along with Florida Medical Entomology Laboratory's Phil Lounibos stating there is no supporting background evidence that GM mosquitoes would solve a dengue problem. All of this and more makes a GM mosquito release seem like an expensive, pointless and potentially risky proposal.

mariela fajardo
mariela fajardo

Dengue is an infection produced by those arthropods (mosquito) who have in their prosboscis the disease infecting each host when they are bite by the insect, at least of thousand of cases is seeing all around of USA and the problem it is not only with the A. Aegipty, because we need to realize that in California, in St. Louis it is a common the encephalitis produced by the bite of the mosquito , the Aedes Gambia, Culex Pipiens Quinquefasciatus, Culex Pipiens Pipiens, Culex Nigripapuls, and arthropodo-borne viruses (arboviruses) it is a problem that concern all the community in general, and the CDC needs to take a inmediately decisions to prevent the spread of this virus infections, the same with the colaborations of those companies that have the chemical to remove the large population of mosquito and prevent their offsprings,(progeny) to grow and the transmission of the disease to a large populations,

Budgielover
Budgielover

I don't know about this. Mosquitoes are at the bottom of the food chain, and while they're detrimental to humans, they're a very important part of the ecosystem, eaten by birds, fish, and bats. They also help pollinate crops and plants. While people do not need mosquitoes, they love birdwatching and fishing, two things that may be impacted severely. This experiment may not be too harmful to the environment if it's only going to kill one species of bug, but it it definitely not something to be taken lightly. If there's complications, the ramifications could be enormous. Why not take some time to get third-party analysis and opinions from other environmental experts?

Jason
Jason

Every time I hear "genetically modified" it gives me the creeps. Remember Africanized bees? We may end up with mutant mosquitoes the size of pidgeons, and Key West residents still suffering from Dengue fever. By the way Natasha Marie, I demonize ALL mosquitoes. They are a pain in the a.. when you try to do anything outdoors in the summertime. I'd be willing to pay a pretty-penny for any device that would kill ALL the mosquitoes in a radius of 100 yards when I'm out in the yard. They can have the Everglades...

Natasha Marie Agramonte
Natasha Marie Agramonte

Fair and thorough analysis of this topic that isn't so quick to demonize GM mosquitoes like many people that don't understand the science are apt to do. Also addresses some of the valid concerns of Key West residents and responses to some of those concerns from mosquito experts, some of whom I'm personally familiar. Overall, an excellent article with few mistakes (only one that I caught ... Aedes aegypti is the not only species of mosquito in South Florida capable of spreading dengue virus, but it is the primary vector species in that area)

 
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